Apprentice answer

Why does a reversed backdraft damper stop exhaust airflow

2nd YearGrease Duct & Specialty ExhaustCheck first

Backdraft dampers are directional. If the fan closes the blades instead of opening them, pull and reinstall the damper in the correct airflow direction.

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Plain-English answer

A backdraft damper is supposed to open with fan flow and close when the fan shuts off. If it is reversed in a louver sleeve, the fan can press the blades shut and make the system look blocked.

Check the airflow arrow, blade swing, and fan direction. Remove the damper frame, flip it to the correct direction, and test that the blades swing freely before reconnecting the duct or sealing the sleeve.

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The backdraft damper at [location] appears reversed; the fan flow is closing the blades. I checked blade swing and airflow direction. Do you want me to pull and flip the damper frame?

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Use this as training guidance. Foreman direction, approved drawings, project specs, manufacturer instructions, employer safety policy, and AHJ/code requirements always control the final answer.

Why does a reversed backdraft damper stop exhaust airflow

Plain-English answer

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